Method of firing retort furnaces



sept. 3o 1924.

K 1,510,045 D. T. DAY

METHOD oF FIRING Rmom' FURNAcEs Filed June 15 192:5

yt! j N O' y m W l S llllm Q l N fj* M Y `lftatented Sept. 30, 1924.

NITED s DAVID T. DAY, OF WASHINGTUN, DISTRICT OF OOLUMBM.

METHOD OF FIRING RETORT FURNACES.

Application led .Tune 15,

To all whom it may concern.'

Be/it known that ll, DAVID T. DAY, a citizen of the United States, residing in the city of lVashing-ton, District of Columbia, have invented certain new and useful lmprovements in Methods of Firing Retort f tially saved.

In the distillation of oil shale, it is customary to run crushed shale through a screw conveyor retort tube in a furnace. The crus ing ofthe shale produces a mixture of l Inps and dust, the latter material bein relatively undesirable because it tends to clbg the apparatus and become a sticky oil mud. The waste shale or spent shale as it is discharged from the retort is quite well exhausted of its volatilizable matter and is chiefly in the form of lumps of shale in which and on which carbon orcoke has been deposited as a result of the destructive distillation within` the retort.` This spent shale as it leaves the retort is nearly dull red with heat, and about ready to burn fas soon as suiiicient air is provided. However, the coke deposited on the lumps will not burn with sufficient llame to satisfy the requirements of a fuel. 0n the other hand,

vfresh shale dust or fines contains suflicient natural fresh oil to burn with a substantial flame. This invention is therefore directed to combining hot spent shale and fresh shale Adus-t so as to use. the useful qualities of both of these otherwise waste materials. The resultant effect is a highly satisfactory fuel suitable immediately for heating re- `torts. The invention also includes details of the particular method of combining the hotspent shalel with the fresh shale.

The above and other details and advantages are described and claimed in the following specification and claims, and one form ofl apparatus suitable for conducting 1923. Serial No. 645,632.

the method and preparing the fuel is illustrated on the attached sheet of drawings, on which the single ligure represents in vertical sectional elevation, a retort within a furnace, a separator for separating shale into fines and lumps, and a travelling grate onto which the hot spent shale and fines are deposited at substantially the same location.

Referring in detail to the apparatus which is illustrated rather diagrammatically, 1 indicates a receiving hopper for fresh shale such as comes from a crusher, not illustrated, and which is a mixture of dust and lumps. 2 indicates a rotary screen separator driven by a pulley 3 from any suitable source of power. The dust or fines which passes through the screen drops into a hopper 4 and through a pipe 4B to the outlet end 4b thereof within a fuel mixing hopper adjacent the furnace grate, as will be described. A valve 4 is positioned in the down pipe 4a to regulatethe amount of nes deposited on the grate. Lumps of shale are discharged from the lower end of the. separator into a hopper I5 positioned at v the receiving end of the retort which will now be described.

The retort structure yincludes a furnaceV having the enclosing walls 6,with av fire box 7, and a stack v8. The ,front end of the furnace next adj acent. the down pipe 4* and the hopper 5 is provided with a lowery opening 6a in which is located a mixing hopper which will be described. Within the furnace walls and extending substantially horizonA tally above the fire box are the .retort tubes in which the lumps of shale are to be treated. These tubes are indicated by an upper tube 9 and a lower tube 10, in which are respective screw conveyors 9a and 10, which in turn are operated by the respective gears 9b and 10b, located at the exterior of -the furnace wall 6 and mounted on projecting ends of the conveyor shafts. A drive wheel 11 is secured to the shaft on which the gear 10b is mounted and serves to rotate the screw conveyors and is driven by any suitable source of power. lt will be observed that the gears 9" and 10b are meshed together, and hence the gears must revolve in opposite directions and correspondingly cause the conveyors to feed in opposite directions.

v Shale is admitted from the hopper 5 through an upper rotatable valve 12 to the adjacent end of thetube 9 and is passed through the length of that tube and finally trated in detail.

dropped at the extreme opposite end into the conveyor tube 10, and thencepassed in a reverse. direction, to the left in the drawing, and finally ,discharged through the rotatable valve 13 into a fuel mixing hopper 14 and onto the top of a traveling grate.

The traveling grate 15 is illustrated dia-, grammatically and is preferably formed of a series of connected elements, thus forming a'. continuous grate. One end. of it is mounted on a horizontally extending sprocket member end support 16, located adjacent the front opening 6a, and preferably on the outside of the furnace Wall. A corresponding end support 16a is located at the opposite end of the furnace and in'such a position that the grate may discharge the spent fuel as the connected elements of the grate pass around the support 16a. It will be understood that the front support 16 and the rear support 16a will ,be as Wide as the width 0f the grate and that they may be likened to longated cylindrical sprocket Wheels or composed of a plurality of individual sprocket wheels arranged side by side and keyed on or revolving freely on a central supporting shaft extending horizontally transverse to the direction 0f movement of the rate bed. Such details do not form a part ofg the present invention, and are therefore not illus- Power means, not indicated, may be applied `to either of the support's 16 or 16a, but is preferably applied to 16, because it is at the cooler portion of the furnace. Other supporting means may be used beneath the grate intermediate of 16 and 16, to support the weight of the grate according to vthe requirements of traveling grate furnace practice. A down chute 17 is positioned adjacent to and beneath the supportc16, to collect the fuel discharged from 'the grate and deposit it in the ash pit 18, which latter may be reached from the exterior at the rear of the furnace through an opening 6b in the furnace wall.

The method of firing the retort and providing the fuel thereforJ will now be described. After the lumps of shale are introduced into the retort tubes they undergo destructive distillation effected by the heat from the furnace, and gases and vapors are led off through the pipe 8 to suitable condensers, not shown. The spent shale discharged from the lower tube and out through the valve 13 reaches the hopper 14 and grate 15 in a very hot condition. A substantial part of its volatilizable content has been driven off, and some of the material has been cracked in and on the lumps of shale. As a, result the lumps are coated and impregnated with coke, which is in nearly red hot condition. This material, however, While it does not have much flame, is capable of providing great heat. As it is discharged from the valve 13 onto the hopper 14, fresh oil shale fines are admitted from the pipe 4a. It Will be observed that the lower end 4b of the fines inlet pipe terminates substantially directly below the spent shale discharge valve 13. The spent shale .is dumped around and above the pipe end 4l and thus tends to keep the pipe end closed against the discharge of fresh shale until movement of the grate carries material away from the region of the pipe end, drawing along with it a portion of fresh shale from within the pipe. The movement of the grate thus serves to draw as much fuel as is needed from the hopper. By running the grate 15 at a speed such that it takes away the spent shale as rapidly as it enters the hopper, the mouth of pipe 4a may be thus kept free from accumulated hot shale and the fresh shale dust is allowed to slide out of the pipe 1 to supplement the hopper supply until the pipe end is buried again. Thus, a uniform level is maintained in the hopper which is desirable to insure a uniform bed on the grate. The mass of material within the hopper chokes off the passage of air and combustion is not free until the fuel is drawn away from the hopper to position in the fire box beneath the retort tubes.

The fines contain the full content of volatilizable material, and are capable of burning with sufficient flame to assist the het spent shale in the heating of the retort. The fines do not serve as satisfactory fuel when used alone, and they are preferably not introduced into the retort tubes for rea-sons hereinbcfore stated, but when mixed with the hot lumps of spent shale, the resultant bed of fuel is sufficiently open for combustion to proceed rapidly. It is to be noted also that this method makes it possible to heat the lines much more quickly than would he possible if they were treated alone as fuel. The condition of the lunlps of hot spent shale is due to the nature of the treatment in the retort. The distillation is conducted at intense heat. and under conditions characterized by the absence of air or oxygen. If there were suflicient oxygen in the interior of the retort tubes, the material would probably begin te burn before it was discharged from the lower tube. As a result the lumps of spent shale are discharged in condition to immediately begin to burn, and the tendency to ignite is used to advantage by the addition of the flame providing fines.

I claim 1. The method of firing retort furnaces, which method comprises, first, passing oil shale through a retort heated by a furnace and discharging the spent sha-le from the retort in hot condition, and secondly, using the hot spent shale as part of the fuel, for the furnace by adding to it fresh oil shale and passing the mixture on a traveling grate through the furnace of the retort from which retort the spent shale was discharged.

- 2. The method of firing retort furnaces, which method comprises treating fresh oil shale to separate it into fines and lumps, passin the lumps through a retort heated by a urnace, passing the hot spent shale from the retort, and using the spent. shale while yet hot together with the fresh shale fines as the fuel for the furnace.

3. The'method of firing retort furnaces which method comprises treating fresh oi shale to separate it into nes and lumps, passing the -lumps into and through a tubular retort heated from beneath by a furnace and thus subjecting the lumps of shale to a heat treatment suicien't to leave coke on the lumps, passing the hot solid material from the retort and onto a traveling grate, addin fresh shale fines to the solid material w ile yet hot, and passing the mixture through the furnace and beneath the retort.

4. A continuous method of firing retort furnaces, which method comprises treatin fresh oil shale to separate it into nes an lumps, continuously assing the lum `s into and through a tubu ar retort heate from beneath by a furnace and thus subjecting the lumps of shale to a distillationv treatment sufficient to leave coke on the lumps, continuously passing the hot solid material from the retort and onto a traveling grate, continuously adding fresh shale fines to the solid material whilelyet hot, and continuously passing the mixture thro h the furnace and-beneath the retort.

5. e method` of firing retort furnaces, which method comprises treating fresh solid fuel to separate it into lumps and dust, assing the lumps through a retort heated y a furnace, passing the hot lumps so treated from the retort and onto -a 4traveling grate, adding fresh fuel dust to the hot lumps and assingl the mixture through the furnace and eneat the retort.

6. The method of firing retort furnaces, which method com rises treatin freshsolid fuel to se arate it into lumps an dust, assing the umps througha retort heate by shale into the interior of a pile of hot passing the lumps through a retort heated y a furnace, passing the fines to the lower end of a fines inlet pipe terminating adjacent a traveling grate, passing the lumps from the retort as hot spent shale and discharging it about the lower end of the nes inlet pipe and onto the traveling grate, re

4leasing lines from the inlet pipe and into the hot spent shale, and using the mixture of hot shale with the fresh dust as the fuel for the retort furnace.

8. The method of firing retort furnaces, which method comprises treating fresh oil shale to separate it into fines and lumps,

assing the lumps through a retort heated y a furnace, passing the lines to the lower end -of afines inlet pipe terminatin in a fuel mixing zone, passing the lumps o shale while yet hot from the retort and into the fuel mixing zone, releasing fresh shale fines from the inlet pi e into the interior of a pile of hot spent s ale, moving the material thus mixed away from the mixing zone and using it as the fuel for the furnace.

9. The method of firing retort furnaces, whichmethod comprises treating fresh oil shale to separate it into lines and lumps, passing the lum throu h a retort heated a furnace an thus su jecting the lumps of shale to distillation, passing the lumps of shale while yet hot from the retort and into a fuel mixing zone, releasing fresh nt shale, moving the material thus mixed rom the mixing zone and using it as the fuel for the'furnace.

In testimony whereof I afix my si DAVID T. AY.

ature. 

